It is known that, in a conventional electric power system, switchgear is disposed in communication with the system. Switchgear conventionally contains an assortment of disconnect switches, circuit breakers, insulators, and fuses, configured to facilitate repairs of the electric power system. Conventionally, switchgear is employed to de-energize portions of the system such that repairs/maintenance may be performed and faults may be cleared, ensuring electric system reliability.
Metal-clad switchgear is compartmentalized utilizing grounded metal barriers for major parts of the circuit, helping minimize fault propagation and to make repairs easier and safer. In addition to compartmentalization, all electrical bus is required to be insulated to further minimize a potential flashover or fault between phases of circuits within the metal-clad switchgear. During maintenance of the switchgear or the power circuits that are protected/switched by this switchgear, standard electrical practices require the use of temporary installed grounding devices to protect the electrician from accidental energization of the power equipment of the system. A permanently installed grounding switch which is utilized only during maintenance could meet this safety practice requirement better than temporary installed devices because it can be remotely operated minimizing contact with the live system and acting as insurance in the event that a switching device or automated system malfunctions and inadvertently closed a switch, or an energy storage device was not discharged. Unfortunately, present grounding switches do not have a way of meeting the ANSI/IEEE metal clad requirement of all live parts or bus being insulated without adding additional compartments, space requirements, and significant cost.
One standard practice in metal-clad switchgear grounding is a Ground and Test Device, colloquially referred to as ‘the widow maker.’ The ground-and-test-device is not a permanently installed device in the switchgear, and therefore must be temporarily connected manually to the live bus of the switchgear. If something goes wrong during the connection or thereafter, the energy of the system is known to be so great that it would severely burn or kill the electrician conducting maintenance or repair. Commonly, the electrician would die weeks later due to infection from the burns.
If there were a grounding/earthing switch that was configured to maintain metal-clad requirements, ensuring proper insulation of all connections, safety of the electricians would be greatly increased, helping to prevent unneeded injuries and/or death.
Thus, there is a need for a new form of grounding/earthing switch that maintains metal-clad requirements while remaining a permanent fixture of the switchgear. Such a switch device is preferably properly insulated during normal or emergency switchgear operation. During maintenance however, the switch is not required to be insulated.